A simple, innovative handcycle propulsion attachment for pushrim manual wheelchairs will be developed that will bring the advantages of handcycle propulsion to wheelchair users in their daily lives. The majority of the 1.4 million manual wheelchair users in the U. S. suffer from Repetitive Strain Injuries (RSI) of the shoulders, elbows, and wrists. These injuries are caused by the awkward biomechanics of pushrim use and the strain caused by inclines, obstacles, and distances encountered outside the home. Ultimately, users are forced prematurely into expensive power wheelchairs, reducing transportability, mobility, and therapeutic physical exertion. The health problems of a sedentary lifestyle result. Studies have consistently shown that handcrank propulsion is significantly more efficient than manual pushrim propulsion and avoids the injury mechanisms that result in RSI. However, currently available handcycles, which use bicycle components and design approaches, are only appropriate for recreational purposes due to excessive weight, bulky size, low maneuverability, and difficult attachment and detachment. The proposed lightweight and compact design: 1) Attaches and detaches easily from most wheelchairs for easy transfer and front access. 2) Is highly maneuverable and retains pushrim functionality while still attached. 3) Has a totally enclosed drivetrain for safety, cleanliness, and aesthetics. 4) Is fully adjustable to any user. 5) Is especially useful for users with limited strength and dexterity, including users with a left/right imbalance, such as stroke survivors who can utilize this design in rehabilitation. In addition to preventing RSI, the proposed design will also extend users'range and encourage physical fitness and participation in society, both of which have been shown in studies to result in net health care cost savings. Society as a whole also benefits from wheelchair users'increased participation. In Phase I, maneuverability, stability, traction, reliability, weight, cost, and attachment feasibility were successfully demonstrated. In Phase II, the steering, drive, control, and attachment systems will be optimized for weight, function, and manufacturability. Finally, industry standard safety and reliability testing will be performed followed by thorough user testing to verify functionality and ease of use. The simple, innovative design, making use of existing components, materials, and fabrication techniques, will be available at a lower cost than any alternative, creating an entirely new product category. With a strong market position, the handcycle attachment is poised to capture a significant share of the $800 million dollar wheelchair market and stimulate further technical innovation in an industry constrained by antiquated structural and technological paradigms. PUBLIC HEALTH RELEVANCE: The majority of the 1.4 million manual wheelchair users in this country will suffer from Repetitive Strain Injuries (RSI) due to the awkward and inefficient biomechanics of pushrim propulsion. Independent studies have consistently shown that the natural and efficient biomechanics of handcrank propulsion avoid these injury mechanisms. The proposed revolutionary handcycle attachment for manual wheelchairs would be the first practical and affordable product that meets all the maneuverability and functional requirements as defined by users.